Evolution
ChEVAR essentials
From a bailout procedure to a standardised therapeutic option: Ten-year anniversary from the first publication of the abdominal use of ChEVAR in symptomatic patients
In this article, Giovanni Torsello tracks the evolution of the chimney endovascular aneurysm repair (ChEVAR) procedure, and how it has developed from a “mere bailout solution” to a “standardised complimentary approach” in the treatment of juxtarenal abdominal aortic aneurysm (AAA). IN 2003, ROY GREENBERG AND colleagues reported their first ChEVAR experience in the Journal of Vascular Surgery.1 This technique, originally born as a bailout solution for emergent situations, has grown in popularity in recent years. Different parallel graft methods (chimney/snorkel, periscope, sandwich) have been developed for the treatment of complex infrarenal, juxtarenal, suprarenal, thoracoabdominal, and aortic arch pathologies.2 These off-theshelf solutions have been adopted in many centres worldwide. However, the preliminary reported results were heterogeneous. While Ohrlander, Hiramoto, and Donas3–5 reported excellent outcomes in terms of 30-day mortality and type I endoleak, higher morbidity and mortality have been described by other authors.6 The reasons for diverging results were the small number of patients included in single-centre cohorts, the wide variety of treated entities, and the varying device combinations used. In order to better understand the value of the technique in different aortic pathologies, and also for standardisation of the procedure, thirteen European and American investigators pooled their experience with 517 cases treated by ChEVAR in the PERICLES registry. An initial point of concern was the high rate of intraoperative type Ia endoleak. In PERICLES,7 the type Ia endoleak rate was 7.9% on completion angiography and decreased to 2.9% by the first postoperative computed tomography angiography (CTA), demonstrating that the majority of ChEVAR gutter endoleaks can be expected to resolve spontaneously. The evaluation of the remaining persistent endoleaks were detected in patients with an insufficient length of the new proximal seal zone. Another key factor associated with a high risk of type Ia endoleak was stent graft oversizing of less than 20%.8 The type Ia endoleak rate January 2021
In this context, PERICLES also demonstrated that the risk of stent instability rises as the number of chimney stent grafts used increases. However, recent data show comparable good results in multiple chimneys when technical details are observed.11 Another point of discussion is the stroke risk after ChEVAR. This complication is related to the antegrade cannulation of the renal and visceral vessels. The use of bilateral upper extremity access was found to be an independent predictor factor associated with a 2.8-fold increased risk for postoperative stroke.12 Using a single-arm access point (e.g. left upper extremity) can reduce the stroke risk after ChEVAR procedures. In case of multiple chimneys, retrograde cannulation and periscope implantation of one or two chimneys can be an alternative, avoiding catheter manipulation at the level of the aortic arch. Further studies are necessary to validate the technique.
in this patient group was 14.3% compared to 2.1% in cases with 30% oversizing. A higher rate of gutter-related endoleaks and low oversizing was found also in patients treated in low volume centres (<20 patients treated per year), showing that experience Giovanni Torsello References plays an important role in the 1. Greenberg RK, et al. Should patients with challenging outcome of this procedure.8 anatomy be offered endovascular aneurysm repair? J Vasc Surg 2003; 38: 990–996. Another important merit of the PERICLES 2. Kansagra K, Kang J, Taon MC, et al. Advanced endografting study is the demonstration that the materials techniques: snorkels, chimneys, periscopes, fenestrations, and branched endografts. Cardiovasc Diagn Ther 2018; play a paramount role when avoiding gutters.9 8(Suppl 1): S175–S83. 3. Ohrlander T, Sonesson B, Ivancev K, et al. The chimney graft: Unpublished data presented at the LINC a technique for preserving or rescuing aortic branch vessels Mount Sinai 2017 Endovascular Symposium in stent-graft sealing zones. Endovasc Ther 2008 Aug; 15(4): 427–32. doi: 10.1583/07-2315.1 (13–14 June, New York, USA) show that 4. Hiramoto JS. Commentary: Multiple chimney grafts for the frequency of this complication was 3.4 total endovascular revascularization of the visceral arteries in the setting of ruptured TAAA: Inventive but let’s wait for times greater in patients treated with stainless the smoke to clear on this one. J Endovasc Ther 2010; 17: steel endoskeleton compared to nitinol 222–223. 5. Donas KP, Pecoraro F, Torsello G, et al. Use of covered devices. This finding was confirmed by the chimney stents for pararenal aortic pathologies is safe and feasible with excellent patency and low incidence of PROTAGORAS study,10 showing excellent endoleaks. J Vasc Surg 2012; 55(3): 659–65. results if the flexible Endurant™ endograft 6. Coscas R, Kobeiter H, Desgranges P, Becquemin JP. Technical aspects, current indications, and results of chimney (Medtronic) is combined with high-radial grafts for juxtarenal aortic aneurysms. J Vasc Surg 2011 Jun; force balloon-expandable chimney stent 53(6): 1520–7. doi: 10.1016/j.jvs.2011.01.067. Epub 2011 Apr 22. grafts (Advanta™ V12, Getinge). The data 7. Donas KP, Lee JT, Lachat M, et al. Collected world experience have demonstrated the importance of specific about the performance of the snorkel/chimney endovascular technique in the treatment of complex aortic pathologies: device combinations to achieve good results, the PERICLES registry. Ann Surg 2015; 262(3): 546–53; discussion 52–3. not only in terms of endoleak reduction, but 8. Donas KP, Usai MV, Taneva GT, et al. Impact of aortic stentalso in chimney occlusion-free survival. Both graft oversizing on outcomes of the chimney endovascular
The ENCHANT registry will provide reliable data on ChEVAR performance.” complications are rare when nitinol-polyester endografts are used. The choice of bridging stent is also important in order to reduce additional use of relining stents, which is associated with significantly worse stent patency (p=0.014).
technique based on a new analysis of the PERICLES registry. Vascular 2019; 27: 175–180. 9. Scali ST, Beck AW, Torsello G, et al. Identification of optimal device combinations for the chimney endovascular aneurysm repair technique within the PERICLES registry. J Vasc Surg 2018; 68(1): 24–35. 10. Donas KP, Torsello GB, Piccoli G, et al. The PROTAGORAS study to evaluate the performance of the Endurant stent graft for patients with pararenal pathologic processes treated by the chimney/snorkel endovascular technique. J Vasc Surg 2016; 63(1):1–7. 11. Taneva GT, Donas KP, et al. Results of chimney endovascular aneurysm repair as used in the PERICLES Registry to treat patients with suprarenal aortic pathologies. J Vasc Surg 2020 May; 71(5): 1521–1527.e1. 12. Bosiers MJ, Tran K, Lee JT, et al. Incidence and prognostic factors related to major adverse cerebrovascular events in patients with complex aortic diseases treated by the chimney technique. J Vasc Surg 2018; 67(5): 1372–9.
Giovanni Torsello is a vascular surgeon at the Institute for Vascular Research, St Franziskus Hospital in Münster, Germany. UC202113392EE
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